Historical clue formulations

• When read forward and then backward, motto that suggests how to interpret this puzzle's starred clues — 2024-05-16
• With 21-Down, catchphrase that provides a hint to eight answers in this puzzle — 2012-01-05
• United — 2003-09-21
• Start of a quote from 20-Across — 2001-10-29
• Part of a unity pledge — 2001-09-12
• Start of a famous motto from literature — 2001-06-15